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a less broad statistical distribution than experimentally observed and presented in the previous section. This result suggests that microsturcutrue features themselves are not the critical flaws in surface micromachined polysilicon ligaments and other features such as surface roughness or other processing induced flaws contribute to the statisitical distribution of failure in these ligaments. ln(ln(1/1-P R )) Fig. 3.5. Weibull plot of maximum stress values obtained form the 100 simulations to 1% strain on the poly12 and poly3 templates. 3.3 Summary 2 1 0 -1 -2 -3 -4 -5 -6 -0.9 -0.85 -0.8 -0.75 -0.7 -0.65 -0.6 -0.55 -0.5 ln(1/σ vm-max ) This chapter discussed a microstructure-based modeling demonstrating that specific microstructure features, boundary triple junctions, can generate a statistical failure distribution in polysilicon ligaments. Boundary triple junctions act as stress concentrators, especially in cases where grain boundaries intersect free-surfaces or where one of the boundaries that forms a junction is parallel to the principal tensile stress direction. However, boundary triple junctions alone do not generate the critical flaw distribution that governs the statistical failure of polysilicon ligaments because Weibull modulus estimates based on these modeling results predict a less broad statistical distribution than experimentally observed. 38 poly12 poly3
3.4 References 3.1 Randle, V., Microtexture Determination and its Applications, The Institute of Materials, Portsmouth, London, 1992. 3.2 Phaneuf, M. W., (1999), Micron, 30, 221. 3.3 http://www.edax.com/technology/EBSD/OIM/index.html 3.4 Buchheit, T.E., LaVan, D.A., Michael, J.R., Christenson, T.R., and Leith S.D., "Microstructural and Mechanical Properties Investigation of Electrodeposited and Annealed LIGA Nickel Structures", Metallurgical and Materials Transactions A, Vol 33A, 2002, p. 539-553. 3.5 Hatherley, M. and Hutchinson, W.B., An Introduction to Textures in Metals, The Institution of Metallurgists, Monograph No. 5, Chameleon Press Ltd., London, 1979. 3.6 Espinosa, H.D. and Zavattieri, P.D., A Grain Level Model for the Study of Failure Initiation and Evolution in Polycrystalline Brittle Materials, Mechanics of Materials, v. 35, 2003, pp. 333-364. 3.7 Madou, M.J., Fundamentals of Microfabrication, Second Edition, CRC Press, London, 2002. 39
Page 1 and 2: SANDIA REPORT SAND2004-1319 Unlimit
Page 3 and 4: SAND2004-1319 Unlimited Release Pri
Page 5 and 6: Contents ACKNOWLEDGEMENTS..........
Page 7 and 8: 6.5 Summary........................
Page 9 and 10: List of Figures Figure 1.1 SEM micr
Page 11 and 12: Figure 6.2 Contact between an elast
Page 13 and 14: Preface Our team was involved in a
Page 15 and 16: strength. The subsequent chapter di
Page 17 and 18: Fig. 1.3. SEM image of cylindrical
Page 19 and 20: Fig. 1.5. Schematic of primary feat
Page 21 and 22: Fig 1.7 Double-hinged pull-tab tens
Page 23 and 24: Fig 1.10. SEM image of optical forc
Page 25 and 26: 2 Strength Distributions in SUMMiT
Page 27 and 28: 2.2 Critical Flaw Size Evaluation T
Page 29 and 30: Fig. 2.5. SEM micrograph of pull-ta
Page 31 and 32: (1) Differences in surface roughnes
Page 33 and 34: 3 The Role Of Microstructure In SUM
Page 35 and 36: crystallographic orientation of a g
Page 37: direction. Also, maximum stress loc
Page 41 and 42: has the advantage of distributing t
Page 43 and 44: and servovalve at a strain rate of
Page 45 and 46: 4.6 References 4.1. TJ Garino, AM M
Page 47 and 48: microscopy studies. As a first step
Page 49 and 50: Fig. 5.2. Orientation imaging of a
Page 51 and 52: Fig. 5.5. Orientation imaging of a
Page 53 and 54: 6 Novel Techniques for Measurement
Page 55 and 56: of adhesion, and, (iv) a smaller co
Page 57 and 58: Force (mN) Fig. 6.5. Typical load-d
Page 59 and 60: 7 Impact of Silane Degradation Due
Page 61 and 62: All samples were coated with alkyls
Page 63 and 64: the friction structure and the cali
Page 65 and 66: 7.4 RESULTS 7.4.1 Simulation of dos
Page 67 and 68: Dose (MeV/g) Fig. 7.4. Results of X
Page 69 and 70: heating on contact angle for PFTS.
Page 71 and 72: the C-C backbone of the PFTS molecu
Page 73 and 74: The increase in static friction for
Page 75 and 76: 8 Friction and Wear of Selective Tu
Page 77 and 78: During processing of microelectrome
Page 79 and 80: actuator. After unloading, the devi
Page 81 and 82: 9 Conclusions and Recommendations T
Page 83: 10 Distribution 3 MS 0889 M.T. Dugg

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